1. Field of the Invention
This invention pertains to padlocks and lock cylinders. More particularly, this invention pertains to a rekeyable padlock and lock cylinder.
2. Description of the Prior Art
Keyable lock cylinders are known in the art, and are used, for example, in keyable padlocks, such as the ones described in U.S. Pat. Nos. 5,363,678 and 5,377,511 issued to Meckbach on Nov. 15, 1994 and Jan. 3, 1995 and U.S. Pat. No. 6,425,274 issued to Laitala et al. on Jul. 30, 2002, respectively, and hereby incorporated by reference in their entirety. Keyable lock cylinders, keyable padlocks or such as these are not typically sold to end users, but rather are first “keyed” by a locksmith and then sold to users. For example, if a consumer purchases one or more lock cylinders or padlocks, it is desirable that the consumer be able to key each of the padlocks to operate with a particular key, such as the consumer's house key. Thus, the consumer would not have to maintain separate and additional keys for each individual lock cylinder or padlock. The lock cylinders or padlocks are provided to a locksmith with a zero-bitted key, meaning that the key has two long, generally parallel edges with no cuts. The locksmith inserts the zero-bitted key into a rotatable core of the cylinder. A stop pin limits rotation of the rotatable core of the cylinder. The stop pin must be removed from the cylinder or—in case of a spring biased stop pin—depressed in order to complete the rotation of the core to align the key profile with a longitudinal row of pin openings or a rectangular slot in an outer casing of the cylinder.
The locksmith determines a pin sequence for each padlock. Specifically, the locksmith selects a predetermined number of key pins to insert in the key pin openings of the core of the cylinder, with each key pin having a specific length and with the key pins ordered in a particular sequence. Generally, a lock cylinder accommodates between 3 and 7 key pins. Typically, the key pins used in a key pin sequence are selected from a group of key pins having a variety of pin lengths.
After the pin sequence is selected and before inserting the key pins through the pin openings, the zero-bitted key is removed from the key profile and a cut key is then inserted into the key profile. One edge of such cut key is cut such that the number, size, and order of cuts in the edge of the key correspond to the number, length, and order of the key pins of the selected pin sequence. The selected pins are inserted into the key pin openings in the specified order of the pin sequence. After all of the key pins are inserted, a shear line is formed and the key is rotated until the key pins are aligned with driver pins and springs that prevent rotation of the cylinder core without the matching key.
Such keyed lock cylinders or padlocks can also be rekeyed to a different particular cut key similar to the above-mentioned procedure. In this procedure the matching original key, i.e. the key the lock cylinder was initially keyed for, is used instead of the zero-bitted key.
As mentioned above, a lock cylinder may accommodate between three and seven key pins. Most common are lock cylinders with five or six key pins. However, keying a lock cylinder having six key pins to a key being cut for a five-pin lock cylinder would result in an inoperative lock cylinder as the free key pin which does not match with any cut of the key would not be able to depress the corresponding driver pin. In other words, the shear line could not be formed, and the cylinder core would be permanently blocked. Frequently, customers desire that a lock cylinder with five key pins be rekeyed to a six key pin type of lock cylinder. As a consequence, a locksmith must spend considerable time for rekeying, i.e. adapting the lock cylinders to customers' needs, particularly when the core must be detached from the lock cylinder so that the unneeded driver pin and the related spring can be removed. This procedure also bears the danger that parts of the lock cylinder get lost.
What is needed is a simplified method, lock cylinder and padlock that enables a consumer or locksmith to key or rekey the lock cylinder or the padlock to a particular cut key and a variable number of pins the key is cut for.
The present invention provides a solution to these and other problems and offers other advantages over the prior art, as will be understood with reference to the summary, the detailed description and the drawings.